Climate, weather and farming: What is history telling us?

As we finish 2012, a year in which the growing season began with an abnormally warm March, was plagued by a severe drought that impacted much of the corn belt, and ended with farmers reporting both record high and record low yields in corn and soybeans, it is fitting to discuss climate and weather and its impact on our agriculture industry.

Last year, the Great Lakes Integrated Sciences and Assessments Center (a NOAA-funded collaboration of Michigan State University and the University of Michigan) and the USDA National Laboratory for Agriculture and the Environment assembled a team of experts to provide input to the U.S. Global Change Research Program’s forthcoming National Climate Assessment. This Midwest Technical Input Team produced a series of reports in 2012, representing the current state of knowledge on what climate change and variability mean to the most critical sectors in the region.

According to the team’s report on historical climate trends, weather and climate remain among the most important uncontrollable variables involved in the region’s agricultural production systems. This is particularly critical for the Midwest as agriculture is a major player in this region’s economy, with over $200 billion in farm gate value.

Let’s begin by discussing the difference between climate and weather. Climate is long-term, based on statistics of observations taken over a large number of years. It is what you can “count-on” in Michigan, for example cool crisp falls, snow in the winter, etc. Weather, on the other hand, is what you get on a day-to-day basis. The abnormally warm March of 2012 was a weather event; this was not typical of Michigan’s climate. This article is the first in a series where Michigan State University Extension will discuss the report as it relates to agriculture in the Midwest. The full report is available on the Great Lakes Integrated Science Assessment website.

In the Midwest, mean temperatures have increased since 1900 and the rate of increase is greater from 1980 through 2010. Precipitation has also increased since the late 1930s. In fact, the last three decades have been the wettest on record. However, the changes in rainfall and temperature have not been the same in all regions or in all four seasons of the year. In Michigan, annual precipitation has remained the same, but we are getting less rain in the fall and more precipitation in the winter and spring. Michigan has gotten warmer over the last 30 years as well with the winter and spring temperatures increasing the most.

Whether you are growing a garden, corn or fruit trees, growing season length is an important factor in the success of your operation. In our region, the growing season has been getting longer. Much of the change has been due to earlier springs. As a result, green-up of overwintering crops in the Midwest is occurring 10 days earlier than just a few decades ago[ja1] . While the increase in growing season has benefits, there is also a downside. When it gets warm early, perennial plants break dormancy early and are then more vulnerable to freeze.

Rain is necessary for crop growth, but is not easily stored. The frequency and intensity of storms has increased since the beginning of the 20th century. On average, about 30 percent of the annual precipitation total across the region comes from just 10 daily events, and the number of these events has increased in recent decades. For Michigan, we see a range of 24 to 36 percent of our annual rain in just 10 daily events.

This is a summary of what historic data tell us about trends over time for the Midwest and, more specifically, Michigan. More details can be found in the full report.

Watching the weather is still an important part of day-to-day management decisions. However, studying historical trends may provide some insight into longer-term planning.